Treating of cast materials in the molten state

ABSTRACT

A method and apparatus is disclosed for treating materials in the molten state. Bubbling gas mixtures and reactants are introduced beneath the surface of the molten material in the riser of the cast to provide an exothermic reaction and delay the solidification of the riser.

United States Patent Wiener May 13, 1975 [54] TREATING OF CAST MATERIALS IN THE 3,208,l 17 941965 Goedecke et al 164/55 3,521,695 7 1970 Diener et al. l64/55 MOLTEN STATE 3,760,862 9/1973 Goudoever et al. 164/55 [76] Inventor: Liviu B. Wiener, 105-40 62nd Rd.,

Forest Hills I 1375 Primary Exar ninerFrancis S. Husar [22] Filed: July 23, 19 Assistant Examiner-Carl A. Rowold No Attorney, Agent, or AminS [52] US. Cl. 164/53; 164/55; 164/66; [57] ABSTRACT I 4 124 [51] Int Cl A method and apparatus is disclosed for treating ma- [58] 56 67 104 terials in the molten state. Bubbling gas mixtures and ]64/123 H reactants are introduced beneath the surface of the molten material in the riser of the cast to provide an [56] References Cited exothermic reaction and delay the solidification of the UNITED STATES PATENTS 2,870,005 I/ 1959 Gebhard 164/53 X 7 Claims, 7 Drawing Figures PATENIEU AY 1 3191s SHEEI 2 OF 3 PMENIED HAY 1 3|975 3,882.92 2

sum 3 OF 3 TREATING OF CAST MATERIALS IN THE MOLTEN STATE BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for treating cast materials, and in particular, to a method and apparatus for bubbling gas mixtures and dipping the reactants beneath the surface of the molten material to delay the solidification thereof and to remove deleterious materials therefrom.

Several inventions of which I am aware, attempt to obtain a uniform casting without deleterious materials or shrink defects, but none have proven to be entirely satisfactory. Oxidant gas and reactant materials have been introduced at various times and pressures to the surface of the molten material in an attempt to slow the setting of the molten material so that uniform impurity free cast object would result. The present invention overcomes the problems of the prior art by providing an automatic means which can be applied to any ingot or mold that is filled with a molten material alloy from a common down sprue.

The present invention further insures rapid oxidation of a highly deoxidant agent by the stirring or agitating of the top portion of a cast riser by the submersed insertion of the deoxidant agent. This causes an exothermic reaction maintaining the riser molten after the cast body has solidified. The present invention may be used with any mixture of one or more highly deoxidant agents combined with a forming slag agent which forms compounds that constitute a fluid slag over the surface of the molten material within the riser that is thermally insulated from the atmosphere.

The gas that is introduced beneath the surface of the molten material is under predetermined pressure, causing bubbling therein, and may be oxidant or inert in nature depending upon the type of treatment to be applied to the molten material. Hereafter, the term oxidant gas is intended to encompass both pure oxygen and mixtures of inert gas and oxygen.

An object of the present invention is to transfer the heat from an exothermic reaction to the top of a casting riser thereby improving directional solidification of a casting or ingot avoiding shrinkage or segregation defects.

Another object of the present invention is to save molten alloy by using risers of decreased size by introducing an exothermic reaction into the riser to delay the solidification thereof.

A further object of the present invention is to modify the chemical composition, structure or remove deleterious constituents from a molten alloy by bubbling an inert gas through reactants submerged beneath the surface of the molten alloy.

An additional object of the present invention is to combine the gas and reactants beneath the surface of the molten alloy material by an apparatus therefore.

SUMMARY OF THE PRESENT INVENTION The method of treating a molten cast body according to the principles of the present invention comprises: supplying a mixture of reactants beneath the surface of the molten body and/or bubbling an oxidant or inert mixture of gases under said surface for producing a surplus of heat to delay the solidification of the upper portion of said cast body to avoid segregation and shrinkage defects.

An apparatus for treating a molten metal cast body according to the principles of the present invention comprises: reservoir means for storing a prescribed amount of reactant to be introduced below the surface of the molten metal, the reservoir means being provided with a bottom opening and inlet and outlet ducts for introducing the reactant, a refractory plunger adapted to be affixed beneath the reservoir means, the plunger including a reaction chamber having an upper opening adapted to cooperate with the reservoir means lower opening and adapted to be immersed in molten metal, an injection plunger slidably mounted for vertical movement within the opening, the injection plunger being hollow and having upper, middle and lower portions, the upper portion being provided with means adapted to introduce gas under pressure, the middle portion being provided with a circular shaped flange adapted to seal the opening, the lower portion being provided with a frusto conical head adapted to seal the opening when in its uppermost position and adapted to release the reactant when lowered therefrom, the head being porous and adapted to be inserted beneath the surface of the molten metal and bubble said gas therethrough, and means for mounting and lowering the refractory plunger to the surface of the molten metal and the injection plunger beneath the surface of the molten metal.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and advantages of this present invention will become more apparent from the detailed discussion hereinafter when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a pictorial representation, taken in partial vertical section, of a mold riser adapted to cooperate with an apparatus utilizing the principles and method of the present invention;

FIG. 2 is an enlarged pictorial representation, taken in vertical section, of the lower and middle portions of the apparatus shown in FIG. 1 in its initial'position prior to the treatment of a molten alloy;

FIG. 3 is an enlarged pictorial representation of the apparatus of FIG. 1 atthe point or release of the reactant into a molten alloy;

FIG. 4 is an enlarged pictorial representation of the apparatus of FIG. 1 with a gas injection plunger bubbling gas beneath the surface of a molten material to cause an exothermic reaction in a riser;

FIG. 5 is a greatly enlarged view taken in elevation of the lower portion of the injection plunger;

FIG. 6 is a pictorial representation of the apparatus of FIG. 1 including a frame and roller means for moving the apparatus of FIG. 1 to the risers of a plurality of molds; and

FIG. 7 is a pictorial representation of the apparatus of FIG. 1 including a modified frame suitable for use with an ingot mold riser.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the figures wherein similar reference characters indicate similar parts in the several figures of the drawings and, in particular, where the numeral 10 generally refers to an apparatus suitable for treating cast materials in the molten state. The apparatus 10 includes an adjustable supporting frame 11 mounted on a cope 12 and surrounds molding box 13. The cope 12 is provided with a riser cavity 14 which is filled with a molten material 15. The size of the cavity 14 may vary according to the size of the riser or surface 16 of the molten material or metal alloy 15. In Contact with the surface 16 of the metal alloy is a refractory plunger 17 which is provided with a circular flange 18 into which is inserted a conventional electric detector 19 and a thermocouple 20 for monitoring the temperature of the molten alloy in the riser. The plunger 17 includes a reaction chamber formed by a casing 26 which is provided with an opening or feeding hole 27.

The casing 26 is affixed to a reservoir or feeding chamber 28 formed by a casing shell 33 which is additionally provided with a lower opening 29 adapted to cooperate with an opening 27 in the casing 26, an'inlet duct 30 which is used to feed the reactants 31 therethrough, in a conventional manner, and an exhaust or outlet duct 32. Attached to the shell 33 is a vibrator 34 which functions to remove molten alloy or slag from the refractory plunger as will be explained hereinafter.

The shell casing 33 is affixed to a housing 35 which is provided with a lower opening and an upper opening 41 in a base 42 and a cap 43, respectively, which are in a vertical line. The cap 43 has affixed therein guide rods 44 whose length may be adjusted by means adjusting nuts 45.

The upper portion 46 of frame 11 is provided with holes 47 which are adapted to receive guide rods 44. In addition, the upper portion 46 has affixed thereto one end of an air cylinder 48. The other end of the air cylinder 48 has a suspension hook 49 which may be used by a crane, not shown, to position the apparatus 10.

Centrally located in the openings 41 and 40 is injection duct 50, which is provided with an input duct 51 and pressure regulator 52, which is adapted to be coupled, via a flexible pressurized hose 53, to a conventional source of oxidant gas, not shown.

The upper portion of injection duct is adapted to be affixed to a plunger rod 54 of the air cylinder 48. A first collar 55 is provided on injection duct 50 which functions as a limit stop of the injection duct 50 for upward movement. A second collar 56 is provided on injection duct 50 below the first collar 55. The second collar 56 is adapted to cooperate with a return spring 57 to raise the injection plunger 50. The first collar 55, and the second collar 56 and spring 57 are all within the housing 35. A circular plug 58 is provided on the injection duct 50 within the feeding chamber 28 and is adapted to seal opening 40 in the housing 35 when the injection duct 50 is at its uppermost position. The lowermost portion of the injection duct 50 is provided with a frusto conical plunger 59 which has a refractory porous plug 60 inserted in the refractory base 61 thereof.

When the injection duct 50 is in its lowermost position plug 58 seals opening 27 pushing the reactants 31 into the molten material 15 and places the plunger 59 beneath the surface of the molten material 15. As noted earlier the depth of insertion of the plungers 17 and 19 may be varied by adjusting the effective length of travel of guide rods 44 by adjusting nuts 45.

Referring now to FIG. 2, which shows an enlarged view of the apparatus 10 and its operation thereof after the reactants 31 have been introduced into the feeding chamber 28, via inlet duct 30. The refracting plunger 17 and injection plunger 59 are both in their uppermost position so that opening 40 is sealed by plug 58 and openings 27 and 29 are sealed by the frusto conical injection plunger 59.

FIG. 3 shows the apparatus l0, after the air cylinder 48 has been pressurized and starts lowering the injection duct 50 thereby opening holes 27, 29 and 40 permitting the feeding of the reactants 31 to the molten material 15. The injection plunger 59 may be maintained in this position for as long a time as is necessary, consistent with the treating of the molten material allowing the reactants to reach the desired temperature. The gas may be permitted to flow through plunger 59 before plunger 59 reaches the surface of the molten material 15, and continued thereafter. During treatment the electronic vibrator 34 increases the stirring effect by its vibrations and prohibits the adhering of reactant particles or slag to the plungers l7 and 59.

There are two critical temperatures that are preferably monitored while treating the molten material 15 in accordance with the principles and apparatus of the present invention. The first critical temperature occurs when the reactants 31 contact the surface of the molten material, since the reactants initially withdraw heat therefrom. The temperature of the molten material, however, is still sufficient for a reaction to occur between the gas, reactants and molten material. Thus, the second critical temperature occurs subsequent to the introduction of the reactants, and this temperature determines the timing of the injection of the plunger 59 beneath the surface of the molten material. These temperatures are determined experimentally, as well as the optimum time for submerging plungers 59 and 17 beneath the surface of the molten slurry consistent with the amount of treatment to be given thereto.

FIG. 4 shows the moment when the exothermic reaction is fully developed and reaction chamber 25 is completely closed by plug 58. The bubbles of gas under low pressure pass through the refractory porous plug 60 penetrating the slurry of molten alloy 15 and reactants 31. The resulting slag and gases rise on the surface of the plunger circular flange 18 of the plunger 17. The fluid slag as a result of this reaction completely covers the surface of the riser 14. The injection of gas is terminated when the plunger 59 is removed from the slags surface. The length of time that the plunger 59 is kept below the surface of the molten material 15 is related to the size of the riser, type of molten alloy, reactants, treatment to be given, and may be a variable controlled by the increase of temperature in the upper part of the riser 14, as measured by thermocouple 20.

FIG. 5 is an enlarged cross sectional view of the frusto conical plunger 59 showing the injection duct 50, refractory porous plug 60 and refractory base 61, mentioned earlier.

FIG. 6 illustrates a vertical view in elevation of the apparatus 10 being affixed to a carriage 62 with rolling beams 63 being positioned above an automatic pouring conveyor 64. To increase the treating handling capacity of the conveyor a plurality of apparatus 10 may be incorporated on an endless belt or supporting rollers may be used to move the molding box or boxes below the apparatus 10.

FIG. 7 shows a modified frame adapted for use with an ingot riser 66, and includes adjustable supporting legs 67 which may be made to conform with the size of riser 66 associated with an ingot mold.

Hereinbefore has been disclosed a method and an apparatus for practicing said method for obtaining improved castings and reduced waste material associated therewith by introducing reactant materials and bubbling gases beneath the surface of the molten material to delay the setting thereof.

lt will be understood that various changes in the details, materials, arrangement of parts and operating conditions which have been herein described and illustrated in order to explain the nature of the invention may be made by those skilled in the art within the principles and scope of the present invention.

What is claimed is:

l. The method of treating a molten cast body beneath the surface of the molten metal in the riser portion comprising the steps of introducing a first refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamber which is substantially segregated from the atmosphere, introducing a second refractory member within the confines of said chamber, moving said second refractory member beneath the surface of said molten cast body, and supplying a bubbling gas through said second refractory member.

2. The method of treating a molten cast body comprising the steps of introducing a first refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamber which is substantially segregated from the atmosphere, supplying a mixture of reactants to the surface of said riser portion within the confines of said chamber, introducing a second refractory member within the confines of said chamber, moving said second refractory member beneath the surface of said molten cast body to cause said mixture of reactants to be moved beneath the surface of said molten cast body, thereafter supplying a bubbling oxidant gas through said second refractory member and beneath the molten surface for producing a surplus of heat to delay the solidification of the upper portion of said cast body to avoid segregation and shrinkage defects.

3. The method of treating a molten metal cast body comprising the steps of introducing a first refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamber which is substantially segregated from the atmosphere, supplying a mixture of reactants to the surface of said riser portion within the confines of said chamber, introducing a second refractory member within the confines of said chamber, moving said second refractory member beneath the surface of said molten cast body to cause said mixture of reactants to be moved beneath the surface of said molten cast body, thereafter supplying a bubbling oxidant gas through said second refractory member and beneath the surface of said molten metal to form a slag of deleterious material within said riser.

4. A method of treating a molten cast body in accordance with claim 1, wherein the gas selected is an oxidant gas and provides an exothermic reaction in the riser portion to delay the solidification thereof.

5. A method of treating a molten cast body in accordance with claim 1, wherein the gas selected is an inert gas.

6. A method of treating a molten cast body in accordance with claim 5, including the step of supplying a mixture of reactants upon the surface of said molten metal within the confines of said chamber, and wherein the movement of said second refractory member causes the mixture of reactants to be moved beneath said molten metal surface.

7. The method of treating a molten cast body comprising the steps of introducing a refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamher which is substantially segregated from the atmosphere, introducing a second refractory member within the confines of said chamber, supplying reactants to the surface of said riser portion within the confines of said chamber, and moving said second refractory member beneath the surface of said molten cast body to cause said reactants to be moved beneath said surface to provide an exothermic reaction to delay the solidification of said riser portion. 

1. The method of treating a molten cast body beneath the surface of the molten metal in the riser portion comprising the steps of introducing a first refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamber which is substantially segregated from the atmosphere, introducing a second refractory member within the confines of said chamber, moving said second refractory member beneath the surface of said molten cast body, and supplying a bubbling gas through said second refractory member.
 2. The method of treating a molten cast body comprising the steps of introducing a first refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamber which is substantially segregated from the atmosphere, supplying a mixture of reactants to the surface of said riser portion within the confines of said chamber, introducing a second refractory member within the confines of said chamber, moving said second refractory member beneath the surface of said molten cast body to cause said mixture of reactants to be moved beneath the surface of said molten cast body, thereafter supplying a bubbling oxidant gas through said second refractory member and beneath the molten surface for producing a surplus of heat to delay the solidification of the upper portion of said cast body to avoid segregation and shrinkage defects.
 3. The method of treating a molten metal cast body comprising the steps of introducing a first refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamber which is substantially segregated from the atmosphere, supplying a mixture of reactants to the surface of said riser portion within the confines of said chamber, introducing a second refractory member within the confines of said chamber, moving said second refractory member beneath the surface of said molten cast body to cause said mixture of reactants to be moved beneath the surface of said molten cast body, thereafter supplying a bubbling oxidant gas through said second refractory member and beneath the surface of said molten metal to form a slag of deleterious material within said riser.
 4. A method of treating a molten cast body in accordance with claim 1, wherein the gas selected is an oxidant gas and provides an exothermic reaction in the riser portion to delay the solidification thereof.
 5. A method of treating a molten cast body in accordance with claim 1, wherein the gas selected is an inert gas.
 6. A method of treating a molten cast body in accordance with claim 5, including the step of supplying a mixture of reactants upon the surface of said molten metal within the confines of said chamber, and wherein the movement of said second refractory member causes the mixture of reactants to be moved beneath said molten metal surface.
 7. The method of treating a molten cast body comprising the steps of introducing a refractory member beneath the surface of the molten metal in the riser portion of said molten cast body so as to form a chamber which is substantially segregated from the atmosphere, introducing a second refractory member within the confines of said chamber, supplying reactants to the surface of said riser portion within the confines of said chamber, and moving said second refractory member beneath the surface of said molten cast body to cause said reactants to be moved beneath said surface to provide an exothermic reaction to delay the solidification of said riser portion. 